1. Field
The apparatus and method of the present invention relate to the field of analyzers having automated pipetting capability, and more particularly, to analyzers capable of testing the linearity of the pipetting needle.
2. Description
Experience has shown that during operation of an automatic pipetting device, deformation of the pipetting needle can occur due to mechanical loads placed upon the needle, for example, by the intended use of the pipetting needle for piercing sample container lids or reagent container lids for the withdrawal of samples or reagents, or by inaccurate positioning of the pipetting needle. Although a very slight curvature of the pipetting needle is usually acceptable (some tolerance is provided for positioning the pipetting needle at the various pipetting positions), if the curvature of the pipetting needle is greater than the permissible tolerance, such curvature may result in malfunction of not only the pipetting device, but also the entire analyzer. Such malfunction can occur hours after the analyzer has begun operation and may cause damage (such as loss of samples and reagents) and expense, including repair costs by the user or an external service, and other expenses resulting from the breakdown of the analyzer.
When automatic pipetting devices of the above kind are used, it is desirable to test the linearity of the pipetting needle by a reliable method, for example, after adjustment of the pipetting needle transport device and before each operation of the analyzer, thereby allowing the pipetting needle to be replaced before operation, if necessary.
The object of the invention, therefore, is to make available an analyzer and a method of the type indicated hereinbefore which allows for reliable testing of the linearity of the pipetting needle.
According to the invention, the first part of the above problem is solved by an analyzer having:
means for guiding the tip of the pipetting needle around the periphery of the top edge of a reference body, the tip of the pipetting needle being guided at a specific distance d from the top edge of the reference body, which distance is a measure of the acceptable curvature of the pipetting needle, and PA1 an electrical circuit for detecting an electrical contact between the tip of the pipetting needle and the reference body. PA1 the tip of the pipetting needle is guided around the periphery of the top edge of a reference body, the tip of the pipetting needle being guided at a specific distance d from the top edge of the reference body, which distance is a measure of the acceptable curvature of the pipetting needle, and PA1 any contact between the reference body and the pipetting needle is detected by means of an electrical circuit.
According to the invention, the second part of the above problem is solved by a method for testing the linearity of the pipetting needle, which is characterized in that:
A major advantage of the analyzer and method according to the invention is that it gives very reliable testing of the linearity of the pipetting needle.